Staff: Mentor

A similar experiment involves charging up two pieces of metal foil that are suspended adjacent to each other in a vacuum jar. When charged up with static electricity (both foils get an excess of electrons), the foil pieces repel each other. Why is that?

If electrons were being released into the air you would probably be able to see them as sparks. Yes, you are right--each strand of hair has an excess of electrons and the excess negative charge on every hair causes the hairs to repel one another! :)